1. Field of the Invention
The present invention relates to a memory device, its access method, and a memory system. The invention is applied to a memory device, etc., on which, for example, a NAND type flash memory is mounted as the memory device.
2. Description of the Related Art
Conventionally, when a host device attempts to access a memory device having a differently defined access mode (new interface (hereinafter, referred to as I/F) protocol), it cannot access thereto because device drivers to drive access modes are different from each other. In addition, in accessing through the differently defined access mode, the memory device needs to replace the device driver of the host device. Because the device driver is installed in firmware on a read only memory (ROM) of the host device and the ROM is impossible to be rewritten.
In contrast, the replacement of the firmware in the host device also requires to replace, for instance, an I/F of the memory device such as an NAND type flash memory. Therefore, the host device becomes impossible to access the NAND type flash memory which the host device has accessed until then.
Accordingly, in such case, the host device has to prepare firmware corresponding to two kinds of access modes for the device driver for the NAND type flash memory and the device driver for the differently defined access mode (new I/F protocol). Or, the host device needs to prepare more than two kinds of device drivers and also select any one of the device drivers from a plurality of device drivers depending on the memory device connected to the host device.
As a result, when accessing a memory device having any access mode of differently defined (new I/F protocol), the host device needs to replace the device driver thereof, so that the memory device results in reducing its convenience.
For instance, Jpn. Pat. Appln. KOKAI Publication No. 2001-266580 discloses a system equipped with a memory device of a common interface method.